Chihiros CO2 Regulator is a superior quality CO2 Regulator designed specifically for use with CO2 diffusers. It is an excellent regulator for the beginner enthusiast or the planted tank professional seeking a sleek, compact, superior quality regulator. Designed with simplicity, the Chihiros CO2 Regulator Solenoid allows users to hand tighten the regulator to the CO2 cylinder or by using Wrenches.